In reciprocating-piston machines, particularly piston-type internal-combustion engines, for the compensation of free mass forces compensating masses are needed which are constituted by revolving unbalanced weights driven by gears coupled with the crankshaft. Such orbiting unbalanced weights may thus be arranged only at the end of a crankshaft in the engine block.
German Offenlegungsschrift (application published without examination) No. 44 41 789 to which corresponds U.S. Pat. No. 5,588,407 issued Dec. 31, 1996, discloses an arrangement in which the crankshaft carries cam disks whose cam tracks are in contact with compensating weights which are designed as pivotal arms extending transversely to and below the crankshaft axis. One end of the compensating weight is coupled with a torsion spring which is affixed to the engine block while the other end of the compensating weight may freely swing back and forth. The torsion spring holds the compensating weight against the cam track of the cam disk with the intermediary of a roller element. This arrangement has the advantage that in case of multi-cylinder in-line engines the compensating weights may be positioned within the crankcase in the region of the crankshaft ends. It is, however, a disadvantage of such an arrangement that if only two compensating weights are used for the entire engine, relatively large compensating masses have to be used with which correspondingly robust torsion springs have to be associated. Accordingly, high pressing forces between the roller element and the respective compensating weight and the associated cam track will result. Such conditions are not adapted for all modes of application. Further, because of the required length of the torsion spring it is not possible to assign a separate compensating weight to each engine piston.